Tangent of Half Angle in Triangle/Historical Note

Historical Note on Tangent of Half Angle in Triangle

In the days before electronic calculators, Tangent of Half Angle in Triangle was often used in preference to the Cosine Rule because it was more convenient for use with log tables.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): half-angle formulae: 2.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): half-angle formulae: 2.